Means for controlling a physical condition



My 30, 1939. o. TAYL OR ANS FOR CONTROLLING A PHYSICAL CONDITION 2 Sheets-Sheet 2 I 012 it J Filed Oct. 13, 1933 INVENTOI DANIEL 6. TAYLOR r 4 W 4 A-rrarm'zvs Patented Ma 30, 1939 UNITED STATES means ron CONTROLLING A PHYSIC 7 common Daniel G. Taylor, Minneapolis, Minn, assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Application October 13, 1933, Serial No. 693,443

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The present invention relates to improvements in the control of a physical condition and has for its principal object the provision of a means by which a physical condition can be maintained at areasonably constant value and by which fluctuations of the physical condition outside of a relatively narrow range within which it is permissible for the condition to fluctuate can be eliminated. The invention has particular utility 10 in the control of temperature or the like for domestic purposes wherein the heat producing apparatus is remote from the space to be heated so that there is a time lag between the generation of the heat and its dissipation into the space to be heated although it is likewise applicable to refrigerating systems or heating systems wherein the supply of steam from a central or municipal heating plant is controlled by means of thermostatically operated valves.

for example, it has been proposed to operate the heat increasing apparatus whenever the temperature of the space to be heated fell below a predetermined temperature, By the time the heat thus supplied began to be dissipated in the space, the temperature thereof had generally fallen considerably below the desired point.

Likewise the heat increasing apparatus would be operated to decrease the supply of heat when a predetermined maximum temperature had been reached but by the time all of the heat supplied had been dissipated into the space to be heated, the temperature thereof would have risen considerably above the desired maximum. These dimculties were due to the inherent lag and overshooting that is present in any heating system and particularly in those types wherein the flre is produced by a. fluid'fuel burner that is started and stopped according to room temperatures.

In the present system as applied to temperature control, a comfort zone is determined within which the temperature may fluctuate slowly without giving a feeling of discomfort. The heat increasing apparatus is then operated at inter- 45 vals sumciently long to maintain the space to be heated within that comfort zone and the intervals are varied or proportioned in accordance with the departure of the temperature from one of the limits of the comfort zone.

More specifically my invention includes a switching mechanism for controlling the operation of a heat increasing apparatus which switch ing mechanism is conjointly controlled by a thermostatic device and a timing device in such a. 56 manner that when the temperature of the space In prior art systems of control, for temperature (c1. zas-4e);

to be heated is above the high limit of the comfort zone, the heat increasing apparatus is not operated to supply heat at any time and when the temperature of the space to be heated is below the low limit of the comfort zone the heat increasing apparatus is operated to supply heat all the time. For any temperature between the high limit and the low limit of the comfort zone, the heat increasing apparatus is operated to supply heat in proportion to the departure of the temperature from one of the limits of the comfort zone. In actual practice it follows that for any constant outdoor conditions (this includes outdoor temperature, wind velocity and direction, and condition of the sun) the temperature of the space to be heated will level oif at some constant value between the high and low limits of the comfort zone. v When there is a change in outdoor conditions, the temperature of the space over an extended period of time and this new value will also be within the comfort zone. In this manner, the temperature of the space to be heated is allowed to fluctuate between the limits of the comfort zone over a long period of time with the result that the change is so slow and of such small magnitude that it is not noticed and occupants of the space to be heated remain in perfect comfort.

A further object of the invention is the provision of a thermostatic device in which a single motor serves to tell the time of day or night, ad- Just the thermostat for day and night settings, indicate whether the thermostat is on day or night setting and additionally cooperates with the thermostat to operate the heat increasin apparatus for varying periods of heat supply dependent upon the departure of the temperature of the space to be heated from one of the limits of a comfort zone.

Further objects of the invention will become apparent as the description thereof proceeds.

For a more complete understanding of the invention, reference may be had to the following description and the accompanying drawings, in which Fig. 1 is a diagrammatic showing illustrative of the principle of the invention,

Fig. 2 is a diagrammatic showing illustrativeof the manner in which the invention may be applied to the well-known holding type circuit arrangement,

Fig. 3 is a. front view of a commercial room thermostat with the invention applied thereto and the cover removed,

to be heated will level off at some new value Fig. 4 is a view similar to Fig. 3 with the clock unit removed and certain parts in section,

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Fig. 5 is a sectional view taken about on line 3-3 of Fig. 3 and with the clock unit removed,

Fig. 6'is a diagrammatic view of the timed adlusting means for the thermostat of Fig. 3,

Fig. '7 is a bottom view of certain of the parts of Fig. 6, 1

Fig 8 is an enlarged view of the cam used to approximate the action shown diagrammatically in Fig. 2, and

Ilg. 9 is a stretchout of the gear train of the clock unit.

Referring to Fig. 1 a bimetallic thermostatic element is shown at I3. The element It is subjected to the temperature of the space to be heated and upon temperature fall engages a contact H which is connected to a motor i2 by a wire H. The motor i2 is herein used to represent any suitable type of heat increasing apparatus. Element #0 is connected to a source of power 13 by a wire I! and motor i2 is also connected thereto by a wire i8. Element i0 is pivoted at i! and a lever i8 is secured to the pivotal point of element It. Secured to lever is to move under the follower l8. The throw of the cam surfaces 20, or the distance through which follower 19 will be moved is equal to a temperature change of 2 at the element it.

With the parts in the position of Fig. 1, the temperature of'the room is between 68 and 70 and the conjoint action of this temperature and the cam mechanism is such that element to is lightly touching contact i l and the motor i2 is operating to supply heat to the room. Cam 2i is moving in the direction oi the arrow and therefore follower" will ride up one of the cam sur: faces 20 which action will rotate element lb about its pivot I I breaking the circuit to motor 52. If the room temperature remains constant, the circuit to motor 12 will remain broken until rollower l9 rides down a cam surface so to a point b at wnlchtime element It will have been rotated about its pivot in a counter-clockwise direction'to such an extent that the circuit to some new points on one of the cam siu'iaccs 20 andthe motor l2 will remain energized until the follower i9 reaches some new point f on the next cam surface 23. This will give operating periods'ofrnotor i2 represented by the distance o and these periods will remain constant as'long as the outdoor conditions do not change again.

It will noted that the operating: periods of motor i2 as represented by g are somewhat longer than the periods represented by d. Likewise it" the outdoor conditions should change so at cause the room temperature to rise above the first value, then the operating periods would become shorter than d. I

If the room temperature rises above 70, element Ill will move so far to the right that it will not engage contact ii even when follower 19 engages the lowermost depressions oi' cam 2| and if the room temperature falls below 68 degrees the element ID will move so far to the left that it will not leave contact H even when the follower l9 engages the peaks of the cam 2|. In this manner the heat increasing apparatus is variably operated for none of the time to onehundred percent of the time upon a minimum change of 2 in room temperature. For any room temperature within the 2" differential the heat increasing apparatus is operated intermittently for periods which vary in proportion to the departure of the temperature from one of the limits of the differential or comfort zone.

Turning now to Fig. 2, the motor I2 is shown as being controlled by the well-known holding type of relay and thermostat. One side of motor other side of motor I2 is connected to a contact 25 by a wire 28. A switch arm 21 which is adapted to engage contact 25 is connected to the other line 28 by a wire 29. Switch arm 21 is controlled by the armature 30 of a relay having a coil 3| Armature 30 also controls a second switch arm 32 which engages a contact 33 upon energization of relay coil 3|. The thermostatic 'I2 is connected to line 23 by a wire 24 and the element Ilia of Fig. 2 controls two flexible blades 34 and 3B which sequentially engage contacts 36 and 31 on temperature fall. Lines 23 and 28 are connected to the high voltage primary 38 of a transformer having a low voltage secondary 39.

As is well known in the art, when blades 34 and 33 engage their contacts 38 and 3! on tempera-v ture fall at the thermostatic element Illa, an emergizing circuit for relay coil 3| is established as follows: secondary 33, wire 40, ,contact 36,

blades 34 and 33, contact 31, wire 4|, relay coil 3i and wire 42 back to the secondary 39. Annature 33 is thereby attracted moving switch arm 21 into engagement with contact to set up a circuit-line 23, wire 24, motor l2, wire 28, contact 2!, switch arm 21, wire 23 to line 28-for motor l2 and also moves switch arm 32 into engagement with contact 33 to establish a holding circuit for relay coil 3| as follows: secondary 38, wire 40, contact 33, blade 34, element Illa. wire 43, contact 33, switch arm 32, wire 44, relay coil 3|, and wire 42 to secondary 39. In this type. of circuit it will be apparent that there is a temperature diiferential between the energizing of motor i2 and the deenergimng thereof, and this temperature 'diiferential is equal to the differential setting of the blades 34-35 and contacts 33-31. In other words motor 12 is not energized until both blades engage their respective contacts, but motor l2 remains energized after blade 33 disengages contact 31 and until blade 34 disen'gages contact 38. For this explanation, the diflerential between these blades andrespective contacts has been taken .as 1 degree.

In order to apply the present invention to a thermostat oi. the holding circuit type it is de sirable for the oifportions 45 of the cam Zia to be higher than the on portions 4t oi the cam Zia by an amount which is equal to the diiier ential setting between the blades 38 and 35. In

this manner when the follower its rides on the 55881511111! immediately drop an amount corresponding to the differential setting between the blades 34 and 85 and likewise when the follower I9a leaves the lower-most part of one ofthe on portions 45, it will be substantially immediately lifted an amount equal to the differential setting of the blades 34 and 35. By this arrangement it is possible to provide the same action on a thermostat of the holding type as would be obtained with a simple cam and a single contact thermostat as shown in Fig. 1. It will be appreciated however, that one might, if desired, use a cam of the type shown in Fig. 1 with a holding circuit type of room thermostat to produce periodic burner operation which varies with departure of room temperature from a selected value termined range within which it is permissible.

for the room temperature to fluctuate plus the fixed differential of the thermostat. Obviously, various shaped cams and various types of thermostats may be employed to provide selected frequencies to cause the burner to operate for amounts of time varying with the departure of the room temperature from predetermined values.

Referring now to Figs. 3 to 9 inclusive, the invention is shown applied to a commercial device commonly termed a room thermostat which is generally indicated at 41 in Fig.3. The room thermostat comprises a base 48 to the lower end of which is secured a bridging member 49 the lower portion 50 being provided with graduations 5I and the upper portion of which is constituted by a piece of electrical and heat insulating material 52. Secured to the under side of insulating member 52 is a second piece of insulating material 53 which is provided with a tongue 54 that extends upwardly and to the left. A curved bimetallic element 55 has one of its ends secured to a bracket 56' which carries a bolt 51 that extends upwardly through the pieces of insulating material 53 and 52 and a nut 58 holds these various parts together there b ing a spring washer 58a interposed between nuts 58 and 52 to obviate play between the parts. Bracket 55 is provided with a slot 59 that receives a small pin 50 which is mounted eccentrically with respect to a larger pin 5| that is rotatably mounted in the piece of insulating material 53. A metallic strip '52 is secured to part of the tongue 54 for strengthening the. same and is provided with an opening for receiving pin 5i. If tongue 54 and metallic strip 52 are rotated about the pivot provided by screw 51, then eccentric pin 50 will engage the sides of slot 59 to cause a corresponding movement of bracket 55 and bimetallic element 55. If pin 5| is rotated, the eccentric pin 50 will cause slight rotation of bracket 55 in respect to insulating maflexible blades'54 and 55 whichcarry contacts 55 and 51. V

-Pivotal1y mounted on base 48 at 58 is a plate 59v provided with a post 10 which is electrically I insulated from plate 59 by means of insulating washers II. A contact screw 12 is threaded into post 10 and cooperates with contact 55 carried by blade 54. A second post 13 is secured to the up per portion of post 15 through an insulating connector 14 and a second contact screw 15 passes through post 13 and cooperates with contact 51 carried by blade 55. Plate 59 is provided with an extension 15 which is bent at right angles to the plane of plate 59 and is provided with a slot 11 which receives a pin I8 that is secured to a member 19 carried by a rod 80. Rod extends behind base 48 and suitably supported in bearings carried by base 48 (not shown) and the lower portion of rod 80 carries a manually operable shifting lever 80 which extends through a slot 82 in base 48. Manually operable lever M is provided with a pointer 83 which cooperates'with graduations 5|. By this mechanism it is possible to shift plate 69 on its pivot 58 by means of lever 8i and this action moves contact screws 12 and 15 toward or away from contacts 55 and 51 so as to provide a manual adjustment for the room thermostat.

Base 48 carries a clock unit which is generally indicated at 84. The ciock unit is diagrammatically shown in Fig. 9 and comprises supporting proper position. Rotor shaft carries a pinion 92 which engages a gear 93 secured to a shaft 94 which is mounted in plates 85 and 85. Shaft 94' carries a pinion 95 which meshes with a gear 95 that carries a pinion 51 which in turn meshes with a gear 98 that is secured to a shaft 99 and pinion I00. Pinion I00 drives a gear and pinion assembly I0 I the pinion of which extends through plate 85 and meshes with a gear I02 which is loosely mounted on a shaft I03. The shaft I03 is the minute shaft of the clock unit and carries a minute hand I04 which cooperates with a clock dial I05. Shaft I03 also carries a pinion I04 which is secured to the shaft in any suitable manner and the pinion I04 is frictionally connected to gear I02 by a friction washer I05. Pinion I04 drives a gear and pinion assembly I05, the pinion of which drives a'gear I01 which is secured to a hollow shaft I08 that is journalled on shaft I03 and extends through dial I05 to carry anhour hand I09. Hollow shaft I08 has a pinion IIO secured to it between plate 88 and dial I05, and this pinion IIO drives a gear III half of which is white and the other half of which is black and may be viewed through a sight opening II2 which is provided in dial I05.

The pinion of gear and pinion assembly I05 also drives a gear and pinion assembly H3 the pinion of which in turn drives a gear 4 carried by shaft II5 to which is secured a 24 hour dial II5. A pair of trip arms ,II1 and H8 are adJustably secured to shaft I I5 by thumb nut II5. These trip arms may be set to correspond to any desired hour of the day and night and cooperate with .atripping mechanism generally indicated at I I9 which in turn operates a clutching mechanism generally indicated at I20 which when operated drives a' cam I2I for one-half of Cam I2I cooperates with shoes a revolution. I22 and I23 that are formed on one of the ends of bell cranks I24 and I25 which' are pivoted to plate 59 at I26 and I21. The other ends of hell cranks I24 and I25 are bent over plate -59 to form pointers I28 and I29 that cooperate'with graduations I30 and I3I formed on plate 59.

Shaft III is driven through one revolution every 24 hours and the trip arms II! and H5 operate tripping mechanism. II 9 and clutching mechanism 5 20 at predetermined hours according to the adjustment of trip arms I" and H8 vin order to move cam IZI through successive half revolutions and the cam IN cooperates with shoes I22 and 523 to shift plate 69 in order to provide day and night adjustments tor the thermostat.

The gear of gear and pinion assembly I05 drives a pinion 932 which is secured to a hand set device Rotation of hand set device I33 simultaneously adjusts minute hand I04, hour hand Hi9, day-night indicator iii, and 24 hOLLl dial lit.

The clock unit 84 as above described and the manner in which plate 55 is shifted for day and night settings of the room thermostat 4'I is not new with applicant and further details of the manner in which the tripping and clutching mechanisms and other parts operate may be obtained by reference to the ctr-pending application of Andrew McNicoll which bears Ser. No. 595,460, and was died February 27, 1932.

A cam I134 is secured to pinion Q32 and the gear ratio between .pinion i322 and minute shaft its is such that earn I34 is rotated once an hour. I

The cam iii iin the present instance is provided with four lobes so as to give 15 minute cycles and an enlarged view of this cam is shown in Fig. 8. The cam H35 as shown in Fig. 8 is designated to operate a thermostatic device of the holding circuit type in accordance with the present invention. Cam i341 operates a lever I 35 which is pivoted to plate 86 of the clock unit as shown at I36. A lever 3? has its lower end secured to tongue 5 its upper end terminating adjacent the lower end of lever H35. The upper end of lever i3] is provided with a bent-over portion I38 which lies under the lower end of lever B35 whereby the lower end oi lever I35 lies between lever I37? and its bent-over portion I38. A contact plate I is adjustably secured to lever i3'l and serves to adjust the point of contact between lever I35 and I3'I whereby the movement imported to lever I3i by cam 63% may be adjusted. Lever I3? is also provided with a substantially horizontal extension I33 to which one end of a coil spring I4!) is secured, the other end of coil spring I40 being fastened to the piece of insulating material. A bracket I52 is secured to bridge member 49 and extends upwardly therefrom, terminating first "below extension !39 and carries an adjustable screw I53 which presents undue rotation of lever l3! in a clockwise direction by spring I40 whereby the clock unit may be removed for repair or replacement without rendering the thermostatic control entirely inoperative.

In operation, motor 89 drives cam I34 in a clockwise direction as viewed in Figs. 3 and 6. The end I42 or lever I35 rides up one of the surfaces l43 of cam I34 which action moves lever I37 in such a direction as to rotate bimetallic element about its pivot 51 in obcounter clockwise direction to bring contacts 88 and 51 closer to or into actual engagement with contact screws I2- and I5 depending upon the temperature of the thermostatic element 55. When one of the high and 35 as previously explained in connection with Fig. 2. When one o! the low points of cam I34 comes into engagement with the end I42 01 lever I35 the cam I34 will stop for a short time until the lost motion of the gear train is again taken up. In this manner the thermostat operates the burner continuously when the temperature of the room is too low, completely discontinues operation of the burner when the room temperaure is too high, and operates the burner intermittently at an indeterminate percentage of each cycle dependent upon the departure of the room temperature from a predetermined value when the room temperature is between the high and low limits.

From the foregoing description it will be apparent that the present invention provides a system and method of control for a physical condition in which the physical condition is allowed to fluctuate within a predetermined zone. This zone, however, can be narrowed down to such an extent as to maintain the physical condition within any desired limits. By correcting the physical condition in accordance with its departure from one of the limits of the predetermined zone, the rate oi change is made so slow that such fluctuations are not detrimental.

Such a system has particular utility in the control of temperature since it is permissible to allow temperature to fluctuate within small predetermined limits ii the fluctuations are not rapid. he applied to heating systems there is probably some relation between the lag in the heating system and the length of time required for moving each lobe of the cam past the cam follower. Although no definite relation has been found as yet experiments indicate that. a fifteen minute cycle as described in the foregoing description is suitable for a warm air heating system and that a thirty minute cycle is suitable for a hot water or steam system but it is to be understood that the time cycles set out herein are merely exemplary and that other time cycles may be used to obtain the best results on particular heating plants.

It will'also be apparent from the foregoing description that the invention provides a novel thermostatic device in which a single motor oper ates a clock, a day-night shifting mechanism for the, thermostatic device, a day-night indicator for indicating whether the thermostat is operating on day or night setting. and a timing apparatus which cooperates with the thermostatic element in the manner above set forth.

Although the invention as herein described as being applied to a clock thermostat of the ordinary type in which the thermostat is automatically adjusted in the morning and in the evening, it will be apparent that the invention is likewise applicable to plain thermostats by the inclusion of a motor which may or may not run at exactly the same speed at all times since any motor which runs with reasonably accurate speeds will be suflicient for the purpose.

. While a specific embodiment of the invention has been shown and described, it should be understood that I'am only to be limited in the purview of the appended claims.

I claim as my invention:

1. A device of the class described, comprising, in combination, a thermostatic member, a contact controlled thereby, a cooperating contact, a supporting member for the cooperating contact, means for adjusting one of said members at predetermined times to obtain day and night settings of the device, a cam for cyclically adjusting the other member within a relatively narrow range several times during the day and night, and a motor for operating the adjusting means and the cam.

2. A device of the class described, comprising, in combination, a thermostatic member, a contact controlled "thereby, a second contact that cooperates with the first contact to control an electrical circuit, a supporting member for the second contact, a day-night shitting device for automatically shifting one of said members at predetermined times during the day and night, a manual device operatively connected to one of said members whereby the same may be manually shifted, a cam for cyclically adjusting one o! the members within a relatively narrow range several times during the day and night, and a motor for operating said day-night shifting device and said cam.

3. In combination, a temperature-changer tor a space whose temperature is to be controlled. a

space-temperature-responsive thermostat havin a predetermined differential associated with the temperature-changer for controlling said changer and operative to place said changer in operation at one space-temperature and to render the changer inoperative at another space-temperature, the second space-temperature differing from the first mentioned space-temperature by an amount .equal to said differential-of the thermostat, and time-operated means associated with the thermostat to adjust the response of the thermostat and including a constantly actuated cam arranged to repeatedly and reversely adjust the thermostat an amount equal to a permissible variation in the space-temperature ata relative- 1y slow rate and, additionally, to adjust the thermostat an amount equal to its above-recited differential each time the direction of adjustment is reversed at a relatively quick rate and in the same direction.

DANIEL G. TAYLOR.

DISCLAIMER 2,l60,042.-Daniel G. Taylor,

Pnrsrcn. CONDITION.

Minneapolis, Minn. MEANS FOR Patent dated May 30 CONTROLLING A 1939. D' claimer filed October 7, 1940, by the assignee, Minneapolis-Honeywell egulator Company.

I Gazette November 5, 1940.]

Herebg enters this disclaimer to claim 2 of said-Letters Patent. 

